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Hi guys was wondering on your thoughts on my problem.

It's now approaching winter and every year I have the same problem, my car does not warm up properly (settle at about midway on the temp gauge) if I drive the car with interior heating on. Obviously this means I get very cold when driving.

Vehicle is fine on warm days or so its linked to air temp. i.e. radiator is cooling air too much for it to properly warm up. Now my first idea is thermostat sticking open or opening too much but then you would think that it would never warm up. It does if the heating isn't on.

What I wnat to check is:

* What is your experience of this?

* What if the reading we get isn't actually the temp of engine but of coolant in/after the heater or in thermostat so its actually cooler than engine temp?

This last point contradicts this picture:

http://www.lingshondaparts.com/honda_ca ... k_03=11478

But there seem to be a number of temp sensor in this picture so maybe the ECU uses a sort of mix of readings?? Particularly what are sensors 12 and 11 and are there other sensors that could be culprits? Sensor 13 seems to be the logical one to base engine temp readings off.

What do you guys think? And failing that share your warming up stategies (fuel economy AND comfort being most important).

Ej9's have problems with the termostat. They tend to bend with time. Mine was leaking fluid so I've replaced it.
The stock unit is for 78 degrees, but there are replacements for above 80. Some people cover the front grill during the winter..and if its too cold that's the only option...especially on the highway.

mynameisowen wrote:Hi guys was wondering on your thoughts on my problem.

It's now approaching winter and every year I have the same problem, my car does not warm up properly (settle at about midway on the temp gauge) if I drive the car with interior heating on. Obviously this means I get very cold when driving.

Simply the thermostat is always stays open. It is common "problem" in civics because thermostats after many years of use they collect sediments from coolant and that results to be always opened.
No big problem the changing it is easy job just to unbolt-bolts 2-3 bolts and changing the coolant.

I have changed a thermostat once in the car's life (purchased new in 1998). Civics don't get warmed easily and thus in the winter you have to wait so as to warm the cabin
But a broken thermostat is a different story. If the temperature variates in the dashboard this means faulty thermostat for sure.

Temperature changes as soon as I put heating fans on so it sounds like a faulty thermostat. Will replace that ASAP (good because I need to bleed coolant when swapping to D16 IM anyway, thanks guys.

Betek can you work your magic and give me a part number for D14A4?

mynameisowen wrote: Betek can you work your magic and give me a part number for D14A4?

It's all here in this forum
viewtopic.php?f=15&t=724&p=11037#p11037

mynameisowen wrote:my car does not warm up properly (settle at about midway on the temp gauge) if I drive the car with interior heating on. Obviously this means I get very cold when driving.

root cause in bold.

when you turn on the heater, you are sapping heat from the engine. the heating coil inside your car is essentially a little radiator and it doesn't have a thermostat sitting in line, so whenever you turn the heater knob, it is *constantly* radiating heat inside the cabin, thus causing your ECT to stay low.

if you ever find yourself in a situation where your thermostat valve is bad or the radiator fan doesn't turn on and causes the engine to overheat, just turn on the heater at full blast and watch the temp needle drop.

Yep this is all very true, however it shouldn't be this bad. I can watch the needle drop as soon as I put the blower fans on which isn't the way it should be. I have to drive behind lorries to get the car warmed up with heating on, I will take the thermostat out and replace it. If it doesn't help then we know that Honda have a poorly designed heating system but my hunch is that my thermostat is just sticking. It's either that or put some cardboard in front of the rad.

mynameisowen wrote:Yep this is all very true, however it shouldn't be this bad. I can watch the needle drop as soon as I put the blower fans on which isn't the way it should be. I have to drive behind lorries to get the car warmed up with heating on, I will take the thermostat out and replace it. If it doesn't help then we know that Honda have a poorly designed heating system but my hunch is that my thermostat is just sticking. It's either that or put some cardboard in front of the rad.

First time I hear that Honda has bad designed system.
I can say that Honda have one of best cooling-heating system.
Ask for example Rover owners they can say lot things about their car system for example failed head gaskets because of bad
engine cooling system.

Honda have designed it's thermostats when they failure to not stay closed but open to prevent engine overheating.
Your problem with interior heating is because of opened thermostat 99%

mynameisowen wrote:Yep this is all very true, however it shouldn't be this bad. I can watch the needle drop as soon as I put the blower fans on which isn't the way it should be. I have to drive behind lorries to get the car warmed up with heating on, I will take the thermostat out and replace it. If it doesn't help then we know that Honda have a poorly designed heating system but my hunch is that my thermostat is just sticking. It's either that or put some cardboard in front of the rad.

dude, replacing the thermostat will not change a thing. it is what I've been trying to say. the interior heating system completely bypasses the main radiator and the heater core acts as a secondary radiator throwing heat inside the cabin. the thermostat valve controls flow to the main radiator but not the heater core. you can change whatever you want but when you turn the heater on, your temperature will drop. short of adding a second thermostat valve inline with the hose that goes to the heater core, there is nothing you can do.